The present invention relates to a shutoff fitting.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Shutoff fittings are provided for blocking a fluid flow through a conduit by using a shutoff element which moves from an open position to a closed position. Shutoff fittings having extremely short closing times are used in particular for immediate reliable shutoff of pipelines for gases, air, or flowable goods, e.g. as protection device in the event of a malfunction caused by rapidly reacting chemical processes. Activation of shutoff systems of this type is triggered e.g. by magnetic valves. Compressed air flows hereby from a compressed air reservoir into a drive cylinder by which the fitting is closed within milliseconds. As a result, harmful media and fire are prevented from spreading as well as propagation of pressure are effectively stopped. After activation, the shutoff fitting can then easily be actively recharged and can be validated by its destruction-free mode of operation. These systems require the presence of a respectively large compressed air reservoir and are dependent on relatively long reaction times of the magnet valves.
Pyrotechnic systems operate with a gas generator which involves electrical ignition of a solid so that reaction gases develop which spread in millisecond range and thus are also useful to trigger the desired closing mechanism. These systems have the drawback that pressure buildup of the reaction gases is not optimal for the application at hand. While hot reaction gases expanded intensely at first to rapidly move the shutoff member from an open position to a closed position. Subsequently, the reaction gas cools down, causing a contraction so that the closing pressure drops at the drive of the fitting. When improperly dimensioning the shutoff fitting, the gas volume can decrease far enough to effect an unwanted reversal, for example of the shutoff plate of a valve. As a result, reliable operation is not ensured.
It would be advantageous and desirable to provide an improved shutoff fitting to obviate prior art shortcomings.